(1) Field of the Invention
This invention relates to antibiotics DO-248-A and DO-248-B of the following Formula I: ##STR2## wherein R is ethyl or isopropyl, and their pharmaceutically acceptable salts. Further it relates to a process for preparing these antibiotics and to anti-acid-fast organism compositions containing as an active ingredient these antibiotics and/or their pharmaceutically acceptable salts.
(2) Description of the Prior Art
Antibiotics have long been clinically used as an anti-tubercle drug and especially aminoglycosides such as streptomycin and kanamycin and semisynthetic macrolides such as rifampicin are generally used in combined drugs with other synthetic anti-tubercle drugs. Generally, it is hard to prevent occurrence of resistant microorganisms where an antibiotic has long been administered and it is a present problem that such resistant microorganisms have been occurred against the anti-tubercle drugs as above mentioned.
Though antibiotic pheganomycins have been known as antibiotics having .alpha.-guanidino-3,5-dihydroxyphenyl acetic acid residue {Proceeding of the 15th Symposium on Peptide Chemistry, 121 (1977)}, DO-248-A and DO-248-B are glycin derivatives and have a distinctly different chemical structure from pheganomycins which are hexa- or heptapeptide derivatives.